Sub noise caused by low power?

I bought a used sub off a friend and was trying to test it out on a old home stereo. It was making a rattling noise around the coil vent could this be me just under powering the hell outta of it its rated at 1500rms and the stereo is only 200x2. I put my multimeter on the coils they are both at 2ohm and when I push on the sub it doesnt sound like its grinding on anything.